Haruki Mishima and Towa Honda are new students at Aokisora High School and best friends; at a convenience store near their high school, Haruki runs into his classmate Miharu Mashiki, a girl he's recognized since he was little.

Disgusted by the irresponsible and talkative Towa, serious class representative Mami has been avoiding him; even when Mami begins avoiding him even more after a certain incident at the convenience store, Towa is undeterred.

Haruki has been unable to focus during swim practcse since the new semester started; though his relationship with Miharu has returned to normal, he still feels as though something is lacking; Miharu begins missing school for some reason.

When Towa spots Miharu having a friendly conversation with their classmate Nasa Sanagi in the waiting room of a hospital, he decides to investigate Nasa's identity and his relationship with Miharu for the sake of his best friend Haruki.

With the Sports Festival coming up, Haruki and Towa's classmates have high expectations for them as members of athletic clubs.

Summer vacation is over, and the Aozora Cultural Festival is approaching; after things went well with Mami at the fireworks display, Towa is delighted to be spending more time with her preparing for the festival.

Haruki worries about Miharu's absence from the cultural festival; Haruki's class encourages Mikado's childhood friend Waka Kisaki to run in the student council elections.

Towa and Mami are steadily growing closer, but they both have concerns about their families; Towa is having trouble with his relationship with his mother, and Mami remains unable to tell her family about her relationship with Towa.

After participating in the three-legged race with Mami, Towa believes they've grown closer; things don't go well when he asks her out on a date.

Towa and Mami seem to return each others feelings, but their concerns push them apart; worried about the couple, Mishima and Miharu put aside their own relationship to discuss if there's anything that can be done for them.

Miharu is scheduled to take time off from school and transfers to another hospital for surgery; she feels both anxious about the upcoming procedure and sad to be moving away from her friends.

Haruki has been concerned since Miharu went to the hospital and visits her every day; Towa and Mami are naturally worried about Miharu as well, but they're also concerned about Haruki.